Oil composition



Patented May 1937 UNITED STATES PATENT OFFICE 011. comosmon Bertrand w. Sto and Everett w. Fuller, Woodbury, N. 3., v to Secular-Vacuum laim.

n, compounds have generally been looked upon as having an opposite tendency, although it has been known that a highly refined oil that is very susceptible to oxidation can be stabilized to some extent by treating it with a small ainount of sul- 5 phur. It has also been deemed necessary to eliminate sulphur from oils, such as transformer oils, which are to be used in contact with copper or other metals which have an amnity for sulphur. y

We have discovered, however, that disulphides 8 of organic compounds are particularly efiective in stabilizing highly refined mineral oils against the formation of acidic materials through oxidation; and that, when used in the small quantities which are sumcient for this purpose, these disulphldes have little or no tendency to attack copper. The present invention consists, therefore, in the addition of one or more of such disuiphldes to a highly refined viscous mineral oil, in the amount necessary to reduce substantially the tendency of the oil to acid formation.

So far as we know, all disulphides oi organic compounds have the. described characteristic, though in varying degrees. The following table shows the eiiect, upon a highly refined viscous oil which normally gave 14112% of acid extract after an oxygen absorptlon test, of the addition of designated small amounts of various organic dlsulphides, the efiect beingindicated by the reduced amounts of acid extract, The oil in question was refined by successive treatments with 25 pounds of 93,1975 sulphuric acid, 25 pounds of 98% sulphuric acid, and about 259 pounds. of 104% sulphuric acid per barrel, followed by neutrallzation and contact with clay.

Acid extract Dmhidfi Quantity e'eegseee dried and weighed. The weight of 1;? meme ents, rated, a corporation of No Drawing. Application June Serial No. 543,396

Uompany, Incorpo- New York In this table the amounts are specified as percentages of the weight of the refined oil.

when the refined oil is such as giveawithout the addition of the disulphide, a smaller acid extract than the 14.32% above specified, a smaller addition of the stabilizing material sumces to reduce the oxidizing tendency to a low figure. For example, in the case of an oil which normally gave 2.94% of acid extract, the addition of 191% of dibenzyl disulphide or .001% of tetra-methyl thiuram disulphide reduced the acid-extract to .12% or less,

are based were made as follows: a sample of the oil was maintained at a temperature of 12:2 C,

and anger: gas bubbled through it slowly for hours. The samplewas then extracted with alcoholic soda, solution, and the extracted material was precipitated by means of an acid, and acid extract varies directly with the susceptibility-oi the oil. to acid formation under the condition of the described test.

\Ihe disulphide may be added to the oil either as a separately prepared material, or as the result of a reaction produced by adding a suitable oompound to the oil and than treating the mixtime to convert the added compound to a dlsul stride. For example, amyl mereaptan may he added, and the mixture then treated with sodium Among the disulphides specifically mentioned above, tetra-=methyithiuram disulphide and s1 henzyl disulphide are those which are, at the same time, highly efie-ctive and most convenient ly available, while they have the low vapor tension which is necessary to avoid loss of the stablllzlng material when the oil is heated to a high temperature. The tetra ngethyl-thiuram olisulphide has a slight tendency to corrode copper, however, so that the dibenzyl disulphide is preferable for some uses, notwithstanding its less powerful efiect,

The invention claimed is:

The combination, with a highly refined viscous mineral oil, of a relatively small quantity of dibenzyl disulphide suilicient to reduce substantiah ly the tendency of the oil to form acidic material through oxidation. 8

- BERTRAND W. STORY.

EVERETT W. FULIER. 

